In the history of lost causes, the figure of George McGovern casts a poignant shadow. His run for the White House in 1972 ended in one of the biggest electoral defeats in American presidential history. The Democrat’s unalloyed opposition to the Vietnam War, his unapologetic espousal of the concept of income redistribution, his belief that government was a solution to America’s problems, his unrepentant liberalism all formed part of what was even then a quixotic campaign. The egalitarianism inherent in McGovern’s agenda seemed too radical to a country that still trembled after the perturbing 1960s, a decade of protests and social experimentation. Instead, Americans re-elected Richard Nixon with his promise of stability and his faith in individual endeavor, finding comfort in his evocation of Eisenhower era family values. Shortly after, the country would be rewarded for its choice with one of its worst political scandals—and Nixon would resign a presidency ravaged by Watergate. “It’s true that I lost to Richard Nixon in the general election by a huge margin,” McGovern would joke years later, when the bitterness had subsided. “But that wasn’t my mistake. That was the mistake of the voters.”

McGovern, who died today at the age of 90, did not make it easy for the electorate to stick with him and the Democratic Party. His 1972 defeat confirmed the end of the astonishing coalition assembled by Franklin D. Roosevelt—one made up of blacks and ethnic minorities, Jews, southern whites, labor. Southern whites, who had begun defecting to the GOP in 1968, completely left the tent; and the urban enclaves of blue collar workers—many the descendants of immigrants from central Europe—fractured in its support for the party because of many of McGovern’s advocacies, including busing. He did little to compromise his views to maintain the party’s traditional pillars of support.

Opposition to America’s military operations in Vietnam would be at the heart of McGovern’s campaign. And he brought to his stance a certainty born of experience. The South Dakota native volunteered to fight for his country in World War II and, as a pilot, flew bombing missions over Nazi-occupied Europe. His views on the Vietnam war would crystalize during his first term as Senator (he had served two terms from 1957 to 1961 as a congressman from his home state). He was particularly affected by the self-immolation of Buddhist monks in Saigon protesting the regime of South Vietnam’s U.S.-backed president. McGovern, however, would continue to publicly support the actions of President Lyndon Johnson in Vietnam, including voting in favor of the Gulf of Tonkin resolution, authorizing the escalation of the war. He would later regret the vote.

By 1969, McGovern was demanding the withdrawal of U.S. troops from the southeast Asian country. He would twice attempt—and fail—to legislate an end to the war; and his public pronouncements against it, including criticism of South Vietnamese corruption, were perceived as increasingly radical in a country that still mostly believed it was a patriotic duty to stand by a U.S. government at war. “Every Senator in this chamber is partly responsible for sending 50,000 young Americans to an early grave,” McGovern said in a particularly combative speech, “This chamber reeks of blood… it does not take any courage at all for a Congressman or a Senator or a President to wrap himself in the flag and say we are staying in Viet Nam, because it is not our blood that is being shed.”

He was part of the polarization of the U.S. compounded by the anti-war protests of the 1960s. In 1968, he made a run for the Democratic presidential nomination that eventually went to Vice-president Hubert Humphrey, who ran after LBJ chose not to seek re-election after a poor showing in New Hampshire. But when he won the 1972 nomination, the shadows of 1968—including the fractious, protest-laden Democratic convention in Chicago—tinged the public perception of McGovern. His defeat in the general election was almost foretold upon his assumption of the nomination. Robert K. Merton, a professor of sociology at Columbia University, told TIME in late September 1972, a little over a month before the election, “What McGovern faces is a cumulative counterreaction to much of the mass protests of the last few years, and he is being penalized for them. He is representing the wave, in the short run, not of the future but of the recent past.”

Several things went wrong. His judgment was called into question when his first choice as veep—Thomas Eagleton—was forced to withdraw after confessing to having had electro-shock therapy for depression. His campaign funds dried up as McGovern’s poll numbers showed no sign of lifting. Finally, the enthusiastic youth vote he counted on did not materialize at the polls. The rest of the country may also have been alienated by the new coalition he had assembled under the Democratic Party banner. As Kevin Phillips had predicted in his 1969 book The Emerging Republican Majority, “the Democratic Party is going to pay heavily for having become the party of affluent professionals, knowledgeable industry executives, social-cause activists and minorities of various sexual, racial, chronological and other hues.”

After going down to spectacular defeat, McGovern would nurse his wounds and even try to find humor in his experience. Still, there would be more bitterness to deal with, including his failure to win re-election to the Senate from South Dakota in 1980, a victim of the phenomenon called Ronald Reagan, who swept up other Republicans who grabbed onto his coattails.

McGovern leaves a legacy that is more than the wistful poignance of pyrrhic liberalism. Among the acolytes that rose from his ashes were Gary Hart—the might-have-been who was McGovern’s campaign manager—and both Bill and Hillary Clinton. He also led the Democratic Party committee that began the reforms that reshaped the presidential nomination process into the complexity of caucuses and primaries they are today—for better or for worse. Derisively called “McGovern’s Rules,” they were meant to open the nomination process to the rank-and-file and get rid of the back-room machinations of party bosses.

While his vision of America may have gone down to defeat in 1972, George McGovern remains a quintessentially American figure—intransigently idealistic, fearless in his conviction, tireless in his pursuit of a better vision of the United States. To the end of his life, he would oppose war. Indeed, in 2009, he warned that President Obama’s war in Afghanistan was looking like “another Vietnam.” McGovern was one of the Cassandras of American politics—never heeded till too late. But his prophecies and admonitions still resonate in the country’s conscience with all the wisdom of a veteran of lost causes. “The highest patriotism is not a blind acceptance of official policy,” he declared, “but a love of one’s country deep enough to call her to a higher standard.”